Acman, you and Rok are both correct; while it's not so apparent on records, at a live performance it was quite clear; "Trane" would take off to parts unknown, he seemed to feel, "If you wanted to hear what you heard on a record, you would have stayed home and played the record".
Tyner would stick with "Trane" as long as he could, but was quick to realize when it was futile, and that's when he would just make a solid foundation for the rest of the group to get behind.
According to Miles, Trane played for Trane on live sets. When this happened, only the musicians in the audience seemed to know what Trane was doing and where he was going.
Yes, Tyner was the glue that kept things together when Trane decided to go on one of his excursions, and Trane must have known that when the muse hit him, and he took off to another galaxy, that McCoy Tyner would keep things together down here on the ground; otherwise, as Rok stated, the music would have slipped into the abyss, and Trane knew that Tyner wasn't going to let that happen.
Enjoy the music.